Internal-combustion engine



2 Sheets-Shoat 1 Filed Jan. 12, 1948 r, !L\\\ \\\\\\\\\\\\Y July 24, 1951 c. T. RHODES 2,561,674

INTERNAL-COMBUSTION ENGINE Filed Jan. 12, 1948 2 Shuts-Sheet 2 w 5% w g: ii

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Ma W? ZZWQ Patented July 24, 1951 OFFICE INTERNAL-COMBUSTION ENGINE Clement Tipton Rhodes, The Lawns, Ascot, England Application January 12, 1948, Serial No. 1,805 In Great Britain January 18, 1945 Section 1, Public Law 690, August 8, 1946 Patent expires January 18, 1965 Claims. (0]. 123-65) This invention relates to sleeve valve, twostroke internal combustion engine of the fuel 1n- J'ection forced induction type wherein air, un-

mixed with fuel, is forced into the cylinder under pressure the fuel being separately injected and the fuel-air mixture being fired either by means of a sparking plug or, in the case of a Diesel or semi-Diesel, either wholly by self-ignition or by self-ignition aided by a hot point. In such engines the requirements of good sleeve valve cooling, good scavenging and good efficiency are extremely diflicult to satisfy.

The principal object of the invention is to provide a sleeve valve two stroke engine, of the type referred to, which shall be of simple construction, having only one sleeve, and which shall be more eflicient and capable of a larger power output for a given size or speed than known two stroke engines of the said type. More specifically the invention seeks to provide a. sleeve valve and air inlet arrangement which shall have inherently good valve cooling, be capable of high speed operation, provide very large efiective valve port areas, and maintain good gas tightness even after long use.

According to this invention a sleeve-valve twostroke engine of the type referred to comprises in combination, an approximately annular air inlet passage extending round the cylinder head, and a single reciprocating sleeve valve between cylinder and piston arranged, when closed, directly to seal oil the inlet passage and formed at or .near the cylinder head end with an approximately annular valve surface adapted to cooperate with a seating on a fixed part of the cylinder head structure to form a directly cooled inlet valve of large area, said sleeve valve also having a plurality of ports positioned to be exposed by the piston at and near bottom dead centre and adapted to co-operate with exhaust ports in the cylinder wall, the inlet valve end of said sleeve valve being so formed that when said inlet valve is closed, pressure within the cylinder tends to hold it closed.

Preferably the sleeve valve is reciprocated by a cam and tappet mechanism operating on it near its crank-case end to move it away from the cylinder head, return movement of said sleeve being, effected by a helical spring under it.

Preferably also the cylinder head is detachable and is formed with a ring seating which cooperates with a ring seating on the upper end of the sleeve valve to constitute the inlet valve.

Theinvention is illustrated in the accompanying drawings in which:

2 Figure 1 is a sectional end elevation of one embodiment,

Figure 2 is a sectional side elevation showing two cylinders of a multi-cylinder engine.

Figure 3 is a sectional side elevation of a por-- tion of the apparatus shown in Figures 1 and 2.

Referring to the drawings each cylinder A contains between the said cylinder and the piston F, a reciprocating sleeve valve B. This sleeve valve is reciprocated for example by means of a cam J, tappet rod H and rocker G, the cam being on a cam-shaft driven from the engine by gears (not shown) in well known way. When the cam J pushes up the tappet rod H, the rocker G bearing on a flange V formed on the lower end of the sleeve valve forces down said sleeve valve against the action of a return spring K. Other means of reciprocating the sleeve valve: may be used. For example, the sleeves could be provided with extensions coming down behind the crank-shaft webs and reciprocation be effected by cams on the crank-shaft, bearing direct on said extensions.

About half way along its length the sleeve valve is provided with ports D which, when uncovered by the piston permit exhaust gases to escape into exhaust passages E surrounding each cylinder and running the length of the engine on both sides.

At its upper end the sleeve valve is formed with a ring seating S co-operating with a seating on the detachable cylinder head. As will be apparent from the drawing the upper end of the sleeve valve and the co-operating part of the cylinder head are so shaped that, when the sleeve valve is closed, pressure within the combustion space of the cylinder will tend to hold said valve closed, pressing the seatings on the sleeve valve and on the cylinder head firmly together. When the inlet valve is open air is forced in from inlet passages T surrounding each cylinder head and communicating with manifolds or passages (not shown) running the length of the engine on both sides. A blower or compressor (not shown) of any known type driven by the engine forces in the air at a suitable pressure which may vary over wide limits depending on design, e. g. from 7 to 30 lbs. per square inch. Fuel, in the form of petrol in the case of a petrol engine is injected by means of a fuel injector N of known construction, the fuel-air mixture being fired at the proper time by a sparking plug M. Of course, in the case of a Diesel or semi-Diesel engine the sparking plug orifice is not provided.

The cylinder and cylinder head are watercylinders proper, however, are in a monobloc casting.

The cycle of operations is as follows: 1mmediately after exhaust gases have been re-' leased through the ports D uncovered by the piston F when approaching bottom dead centre, the inlet valve opens and clean air under pressure from the supercharger is forced in. This gives excellent scavenging, the inlet valve remaining open long enough to allow the exhaust gases to be driven out and closing after a little clean air has also passed out through the exhaust ports. The piston is now moving up and immediately after it has closed the exhaust ports the inlet valve commences to close trapping within the cylinder 2. volume of clean air at a pressure substantially equal to the blower pressure. At this moment, or shortly after, petrol is injected into the cylinder. Further movement of the piston upwards compresses the charge which isfired by the sparking plug at or near top dead centre. The following downward stroke of the piston is the working stroke near the end of which the exhaust ports are opened by the piston once more.

It will be observed that both inlet and exhaust ports are of very large effective areas, the size being limited only by the diameter of the cylinder bore. Moreover the location of the inlet valve end of the sleeve valve as shown in direct external contact with the incoming clean air in the inlet-passages gives very efllcient cooling. This good cooling, in addition to the fact that the explosion pressure tends to hold the inlet valve tight on its seat, results in the maintenance of a high degree of gas tightness over a long period of useful life. In addition the engine is mechanically simple, easy to maintain, reasonably accessible and cheap to make.

What I claim is:

1. A sleeve and piston valved two-stroke internal combustion engine comprising in combination, a cylinder comprising a cylinder head and a cylinder wall, means for forcing air, unmixed with fuel into the cylinder under pressure, means separate from said first mentioned means, for injecting fuel into said cylinder, a

.substantially annular air inlet passage extending round the cylinder head, a single reciprocating sleeve valve between piston and cylinder. a substantially annular valve surface formed on said sleeve valve, a cooperating valve seating surface on a fixed part of the cylinder headinlet valve end of said sleeve valve being shaped to present a free pressure receiving surface accessible to pressure within said cylinder to force said valve surface towards said valve seating surface. 1

2. The invention according to claim 1 wherein the cylinder head isdetachable and formed with a ring-like seating which co-operates with a ring seating on the sleeve valve.

3. The invention according to claim 1 wherein there is a plurality of cylinders cast together each of said plurality having its own separate detachable cylinder head and wherein in each case the cylinder head is detachable and formed with a ring-like seating which co-operates with a ring seating on the sleeve valve.

4. The invention according to claim 1 wherein the cylinder head is detachable and formed with a ring-like seating which co-operates with a ring seating on the sleeve valve, water cooling being provided by means of separate cylinder and cylinder head water spaces which do not directly communicate with one another.

5. The invention according to claim 1 wherein there is a plurality of cylinders cast together each of said plurality having its own separate detachable cylinder head and wherein in each case the cylinder head is detachable and formed with a ring-like seating which co-operates with a ring seating on the sleeve valve, water cooling being provided by meansof separate cylinder and cylinder head water spaces which do not directly communicate with one another.

CLEMENT TIPTON RHODES.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

